Railway Battery Chargers for Cleaner, More Efficient Locomotives
Sep 9, 2022
The replacement of the internal combustion engine (ICE) with the electric motor is a key factor in reducing pollution from automobiles, but the trend extends beyond the road: converting diesel locomotives to electric or hybrid operation is also gaining attention as a means to combat global warming.
For locomotives, switching to electric power offers multiple benefits, including reduced NOx emissions, lower noise levels, decreased fuel consumption, easier maintenance, and higher reliability. In fact, most diesel locomotives do not use the diesel engine to drive the wheels directly. Instead, the diesel engine drives a generator that powers electric motors at the wheels. Since the system is partially electric from the start, it might seem relatively straightforward to remove the diesel engine and draw power directly from existing networks of high-voltage overhead wires.
An all-electric approach works well for fully electrified railroads, but overhead power lines are not always available in train shunting yards. Instead, rail operators are adopting hybrid locomotives (“dual-power“ in railway terminology) that primarily run on battery power, with a small diesel engine powering a generator for auxiliary energy when the battery is depleted. A German cargo rail operator is gradually replacing its diesel units with environmentally friendly hybrid alternatives. The company plans to replace around 900 older locomotives, with the first freight units entering service in 2023 and shunting units following in 2024. Once the hybrid phase-in is complete, the operator expects to reduce energy consumption by 30 percent and save one million liters of diesel annually.
New shunting locomotives rely on an 850V lithium-ion battery pack as the primary energy source, providing the 80-tonne shunter with 500kW of traction power. The system also uses an on-board charger in the 15-20kW range to charge the train batteries while the locomotive is in the depot. That’s where RECOM comes in. Working with one of the largest Tier-One suppliers of railway systems and electrical equipment, our Railway division secured the contract to supply the on-board railway battery chargers for the first 80 hybrid shunting locomotives, with further orders expected.
In this case, RECOM offered a standard design with modified connectors that provides all required features and railway compliance in one compact unit. The design is based on RECOM’s RMOC18k, originally designed for charging on-highway vehicle batteries, but it is also ideally suited to the needs of the railway depot charger.
With a 3-phase 400VAC input supplied from the industry-standard CEE 32A socket, the RMOC18k can generate output power up to 18kW with output voltage up to 920VDC. RECOM handles all railway-relevant approvals and mechanical design for the specialized connections and mounting.
Figure 1 shows the basic RMOC18K and the proposed packaging configuration for the hybrid locomotive application.
An all-electric approach works well for fully electrified railroads, but overhead power lines are not always available in train shunting yards. Instead, rail operators are adopting hybrid locomotives (“dual-power“ in railway terminology) that primarily run on battery power, with a small diesel engine powering a generator for auxiliary energy when the battery is depleted. A German cargo rail operator is gradually replacing its diesel units with environmentally friendly hybrid alternatives. The company plans to replace around 900 older locomotives, with the first freight units entering service in 2023 and shunting units following in 2024. Once the hybrid phase-in is complete, the operator expects to reduce energy consumption by 30 percent and save one million liters of diesel annually.
New shunting locomotives rely on an 850V lithium-ion battery pack as the primary energy source, providing the 80-tonne shunter with 500kW of traction power. The system also uses an on-board charger in the 15-20kW range to charge the train batteries while the locomotive is in the depot. That’s where RECOM comes in. Working with one of the largest Tier-One suppliers of railway systems and electrical equipment, our Railway division secured the contract to supply the on-board railway battery chargers for the first 80 hybrid shunting locomotives, with further orders expected.
In this case, RECOM offered a standard design with modified connectors that provides all required features and railway compliance in one compact unit. The design is based on RECOM’s RMOC18k, originally designed for charging on-highway vehicle batteries, but it is also ideally suited to the needs of the railway depot charger.
With a 3-phase 400VAC input supplied from the industry-standard CEE 32A socket, the RMOC18k can generate output power up to 18kW with output voltage up to 920VDC. RECOM handles all railway-relevant approvals and mechanical design for the specialized connections and mounting.
Figure 1 shows the basic RMOC18K and the proposed packaging configuration for the hybrid locomotive application.
As Figure 2 illustrates, the on-board charging module includes the RMOC18K as the main power converter feeding two battery packs, along with all features required to meet customer specifications, including output voltage and current metering, status indicator lamps, output fuses, reverse voltage protection, and overvoltage protection.
Railway Battery Chargers for Lower Power and Scalable Applications
RECOM also offers several standard battery chargers with cascadable power levels, designed for rolling stock, trackside, or any railway infrastructure. The SA320x and SA500x families are compact battery chargers with single-unit outputs of 3.2kW and 5kW, respectively. They achieve 94% efficiency and include active PFC with a power factor of 0.9 at full load. The battery chargers feature a full range of input protections (inrush current protection, EMI filter, protective fuses) and output protections (overvoltage, overcurrent, short-circuit, and over-temperature).
The chargers also support current sharing for parallel operation, increasing power output or enabling redundant n+1 operation. The units operate on 3-phase 380–440V AC without requiring a neutral connection or high-voltage DC input. They comply with relevant railway and industrial standards such as:
The chargers also support current sharing for parallel operation, increasing power output or enabling redundant n+1 operation. The units operate on 3-phase 380–440V AC without requiring a neutral connection or high-voltage DC input. They comply with relevant railway and industrial standards such as:
- EN 50155
- EN 62368-1
- EN 50121-3-2
- EN 50121-4
- EN 50124-1
- EN 50129
- EN 61373
- EN 45545-2
Other features include monitoring outputs for battery current sensing and an RS485 MODBUS or CAN J1939 interface for data communication.
Applications
